The present invention relates generally to Optical Coherence Tomography (“OCT”), and more specifically to OCT implementations.
In OCT, light from a broad band light source is split by an optical fiber splitter with one fiber directing light to a sample path and the other optical fiber directing light to a reference path mirror. The distal end of the sample path can be interfaced with a scanning device, or the like. The reflected light from the scanning device is recombined with the signal from the reference mirror forming interference fringes, allowing precise depth-resolved imaging or optical measurements to be taken. Conventional OCT thus measures spatially resolved backscattered intensity with a resolution on the order of a few micrometers.
Fourier domain OCT (“FD-OCT”), sometimes known as Spectral Domain OCT (“SD-OCT”), can obtain a high sensitivity and imaging speed. And polarization sensitive Fourier domain OCT (“PS-FD-OCT”) can reveal birefringence, diattenuation, and polarization sampling by measuring the change in polarization state. The implementation of polarization sensitivity into FD-OCT has been demonstrated. However, the FD-OCT systems which implement polarization sensitivity have developed with dual-channel detection paths, with either two separate spectrometers, two separate line-scan cameras, or two separate lines on an area-scan camera to capture in parallel the spectral interferogram for two orthogonal polarization modes. Swept source implementations of PS-FD-OCT have employed two detection channels in a configuration similar to time-domain PS-OCT; however the cost associated with an additional dual-balanced photoreceiver and digital acquisition channel can be substantial. These approaches necessitate very precise relative alignment between the two polarization-detecting elements to overcome misalignment-associated artifacts, such as birefringence offset. Additionally, the monetary cost associated with additional detection elements is substantial. The present invention attempts to solve these problems, as well as others.